1. Field of the Invention
The present invention relates to devices, software applications and networks that utilize data that is sent or received over data communication or computer networks. In particular, the present invention is directed to methods for handling datagrams between network devices that have differing capabilities. The processor and methods described provide the ability to control the forwarding of datagrams by remapping field data to allow for greater handling capacity.
2. Description of Related Art
As computer performance has increased in recent years, the demands on computer networks has significantly increased; faster computer processors and higher memory capabilities need networks with high bandwidth capabilities to enable high speed transfer of significant amounts of data. The well-known Ethernet technology, which is based upon numerous IEEE Ethernet standards, is one example of computer networking technology which has been able to be modified and improved to remain a viable computing technology.
Based upon the Open Systems Interconnect (OSI) 7-layer reference model, network capabilities have grown through the development of repeaters, bridges, routers, and switches, which operate with various types of communication media. Collectively, with respect to the present invention, all of these may be referred to as network devices. Switches, as they relate to computer networking and to Ethernet, are hardware-based devices which control the flow of datagrams, data packets or cells based upon destination address information which is available in each packet. A properly designed and implemented switch should be capable of receiving a packet and switching the packet to an appropriate output port at the maximum speed capability of the particular network.
Referring to the OSI 7-layer reference model discussed previously, the higher layers typically have more information. Various types of products are available for performing switching-related functions at various levels of the OSI model. Hubs or repeaters operate at layer 1, and essentially copy and “broadcast” incoming data to a plurality of spokes of the hub. Layer 2 switching-related devices are typically referred to as multiport bridges, and are capable of bridging two separate networks. Bridges can create a table of forwarding rules based upon which MAC (media access controller) addresses exist on which ports of the bridge, and pass packets that are destined for an address which is located on an opposite side of the bridge. Bridges typically utilize what is known as the “spanning tree” algorithm to eliminate potential data loops; a data loop is a situation wherein a packet endlessly loops in a network looking for a particular address. The spanning tree algorithm defines a protocol for preventing data loops. Layer 3 switches, sometimes referred to as routers, can forward packets based upon the destination network address. Layer 3 switches are capable of learning addresses and maintaining tables thereof which correspond to port mappings. Processing speed for layer 3 switches can be improved by utilizing specialized high performance hardware, and off loading the host CPU so that instruction decisions do not delay packet forwarding.
In addition, as new network devices are developed, new capabilities are developed in response to new issues that arise or have arisen with previous network devices. Some of these issues arise because customers of the prior network devices have certain requests or conditions that should be met or because new methodologies have been developed that are improvements over prior methodologies. Often times, the newer network devices must be integrated with the older network devices to provide the proper capacity, i.e., for example, a total number of ports in a combined amalgamation of devices having a certain throughput.
However, this may introduce difficulties in that while the newer devices are usually “backward compatible,” the combination of devices can not necessarily utilize all of the benefits of the newer devices. One such issue occurs when an older network device has a more limited capacity in the number of other devices it can be connected to and a limited number of total ports that can be considered in making decisions on how to handle and forward received datagrams. Thus, there is a need in the prior art to determine methods that allow for greater functionality of combined chip sets and network devices are utilized together to achieve capacity and functionality objectives.